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#5591

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This commit is contained in:
Nikolaj Bjorner 2021-10-13 21:38:36 -07:00
parent 7b341313d5
commit f60ed2ce92
2 changed files with 53 additions and 41 deletions
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93
src/smt/theory_seq.cpp
View file

@ -562,55 +562,66 @@ void theory_seq::mk_decompose(expr* e, expr_ref& head, expr_ref& tail) {
/*
\brief Check extensionality (for sequences).
*/
bool theory_seq::check_extensionality(expr* e1, enode* n1, enode* n2) {
dependency* dep = nullptr;
expr* o1 = n1->get_expr();
expr* o2 = n2->get_expr();
if (o1->get_sort() != o2->get_sort())
return true;
if (ctx.is_diseq(n1, n2) || m_exclude.contains(o1, o2))
return true;
expr_ref e2(m);
if (!canonize(n2->get_expr(), dep, e2))
return false;
m_new_eqs.reset();
bool change = false;
if (!m_seq_rewrite.reduce_eq(e1, e2, m_new_eqs, change)) {
TRACE("seq", tout << "exclude " << mk_pp(o1, m) << " " << mk_pp(o2, m) << "\n";);
m_exclude.update(o1, o2);
return true;
}
for (auto const& p : m_new_eqs) {
if (m_exclude.contains(p.first, p.second)) {
TRACE("seq", tout << "excluded " << mk_pp(p.first, m) << " " << mk_pp(p.second, m) << "\n";);
return true;
}
}
ctx.assume_eq(n1, n2);
return false;
}
bool theory_seq::check_extensionality() {
unsigned sz = get_num_vars();
unsigned_vector seqs;
dependency* dep = nullptr;
expr_ref e1(m);
for (unsigned v = 0; v < sz; ++v) {
enode* n1 = get_enode(v);
expr* o1 = n1->get_expr();
if (n1 != n1->get_root()) {
continue;
}
if (!seqs.empty() && ctx.is_relevant(n1) && m_util.is_seq(o1) && ctx.is_shared(n1)) {
dependency* dep = nullptr;
expr_ref e1(m);
if (!canonize(o1, dep, e1)) {
// check extensionality for sequence arguments of nth_u
// two occurrences of nth_u(a,x), nth_u(b,y) must induce comparing sequences a, b
// whenever x = y
if (m_util.str.is_nth_u(o1) && n1->is_cgr()) {
auto* r0 = n1->get_arg(0)->get_root();
auto* r1 = n1->get_arg(1)->get_root();
if (!canonize(r0->get_expr(), dep, e1))
return false;
}
for (theory_var v : seqs) {
enode* n2 = get_enode(v);
expr* o2 = n2->get_expr();
if (o1->get_sort() != o2->get_sort()) {
continue;
}
if (ctx.is_diseq(n1, n2) || m_exclude.contains(o1, o2)) {
continue;
}
expr_ref e2(m);
if (!canonize(n2->get_expr(), dep, e2)) {
for (auto* p : r1->get_parents())
if (p != n1 && p->is_cgr() && m_util.str.is_nth_u(p->get_expr()) &&
!check_extensionality(e1, r0, p->get_arg(0)->get_root()))
return false;
}
m_new_eqs.reset();
bool change = false;
if (!m_seq_rewrite.reduce_eq(e1, e2, m_new_eqs, change)) {
TRACE("seq", tout << "exclude " << mk_pp(o1, m) << " " << mk_pp(o2, m) << "\n";);
m_exclude.update(o1, o2);
continue;
}
bool excluded = false;
for (auto const& p : m_new_eqs) {
if (m_exclude.contains(p.first, p.second)) {
TRACE("seq", tout << "excluded " << mk_pp(p.first, m) << " " << mk_pp(p.second, m) << "\n";);
excluded = true;
break;
}
}
if (excluded) {
continue;
}
ctx.assume_eq(n1, n2);
}
if (!n1->is_root())
continue;
if (!m_util.is_seq(o1))
continue;
if (!seqs.empty() && ctx.is_relevant(n1) && ctx.is_shared(n1)) {
if (!canonize(o1, dep, e1))
return false;
}
for (theory_var v : seqs)
if (!check_extensionality(e1, n1, get_enode(v)))
return false;
}
seqs.push_back(v);
}
@ -2368,7 +2379,7 @@ void theory_seq::validate_fmls(enode_pair_vector const& eqs, literal_vector cons
theory_var theory_seq::mk_var(enode* n) {
expr* o = n->get_expr();
if (!m_util.is_seq(o) && !m_util.is_re(o))
if (!m_util.is_seq(o) && !m_util.is_re(o) && !m_util.str.is_nth_u(o))
return null_theory_var;
if (is_attached_to_var(n))

1
src/smt/theory_seq.h
View file

@ -458,6 +458,7 @@ namespace smt {
void add_unhandled_expr(expr* e);
bool check_extensionality();
bool check_extensionality(expr* e1, enode* n1, enode* n2);
bool check_contains();
bool check_lts();
dependency* m_eq_deps { nullptr };